1. Field of the Invention
The invention relates to a semiconductor device, particularly, a package type semiconductor device and a method of manufacturing the same. The invention also relates to a camera module having a package type semiconductor device.
2. Description of the Related Art
A CSP (chip size package) has received attention in recent years as a new packaging technology. The CSP is a small package having about the same outside dimensions as those of a semiconductor die packaged in it.
A BGA (ball grid array) type semiconductor device has been known as a type of the CSP. In the BGA type semiconductor device, a plurality of ball-shaped conductive terminals made of metal such as solder is arrayed on one surface of a package and is electrically connected to a semiconductor die mounted on the other surface of the package.
When the BGA type semiconductor device is mounted on electronic equipment, the semiconductor die is electrically connected to an external circuit on a printed board by bonding the conductive terminals to wiring patterns on the printed board.
Such a BGA type semiconductor device has advantages in providing a large number of conductive terminals and in reducing a size over the other CSP type semiconductor devices such as an SOP (small outline package) and a QFP (quad flat Package), which have lead pins protruding from their sides. Therefore, the BGA type semiconductor device has a wide field of application, for example, as an image sensor chip of a digital camera mounted on a cellular phone or the like.
FIGS. 15A and 15B show an outline structure of the conventional BGA type semiconductor device. FIG. 15A is an oblique perspective view showing the front side of the BGA type semiconductor device. FIG. 15B is an oblique perspective view showing the back side of the BGA type semiconductor device.
A semiconductor substrate 104 is sealed between a first glass substrate 102 and a second glass substrate 103 with resin layers 105a and 105b of epoxy resin or the like interposed therebetween in the BGA type semiconductor device 101. A plurality of conductive terminals 106 is arrayed in a grid pattern on a surface of the second glass substrate 103, that is, on a back surface of the BGA type semiconductor device 101. The conductive terminals 106 are connected to the semiconductor substrate 104 through second wirings 109. The plurality of second wirings 109 is connected with aluminum wirings extending from inside the semiconductor substrate 104, making each of the conductive terminals 106 electrically connected with the semiconductor die 104.
More detailed explanation on a cross-sectional structure of the BGA type semiconductor device 101 will be given hereafter referring to FIG. 16. FIG. 16 shows a cross-sectional view of the BGA type semiconductor devices 101 separated in individual dies along a dicing line.
A first wiring 107 is provided on an insulation film 108 formed on a front surface of the semiconductor substrate 104. The front surface of the semiconductor substrate 104 is attached on the first glass substrate 102 with the resin layer 105a. A back surface of the semiconductor die 104 is attached on the second glass substrate 103 with the resin layer 105b made of epoxy resin or the like.
One end of the first wiring 107 is connected to the second wiring 109. The second wiring 109 extends from the end of the first wiring 107 onto the surface of the second glass substrate 103. The ball-shaped conductive terminal 106 is formed on the second wiring 109 extended onto the second glass substrate 103. A protection film 110 made of a solder resist or the like is further formed on the surface of the second wiring 109. Relevant technologies are disclosed in Japanese Patent Application Publication No. 2002-512436.
However, there is a problem that a process of manufacturing the described conventional semiconductor device 101 is complex. Furthermore, the reliability of the described semiconductor device 101 is not enough because of its complex structure. For example, there is a possibility that the first wiring 107 and the second wiring 109 of the BGA type semiconductor device 101 are disconnected at a point of contact between them since the area of the point of contact is very small. There is also a problem of insufficient step coverage of the second wiring 109.